Evidence used
- No CISA KEV confirmation is currently recorded.
- EPSS is 0.43% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2026-49276High confidence
Kirby: Self cross-site scripting (self-XSS) in the writer field
getkirby · kirby
Official source article: GitHub GHSA-RHJ6-R49H-5932 ↗. Check the applicable product and release in the original source.
7.4HighCVSS 4.0
Within 7 days
Fix not verifiedHigh technical severity; prioritise exposed affected systems while verifying vendor guidance.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityHigh→Operational priority:High, unchanged from published severity.unchanged
Compensating controls
- Restrict the affected network interface to trusted sources where business-safe.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs getkirby kirby and falls inside the recorded affected range.
- Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Open-source package ranges4 source-attributed ranges
These OSV and GitHub advisory ranges apply only to the named package and ecosystem. A listed fixed version is not a universal product patch or proof that an update is installed.
| Ecosystem and package | Affected range | First fixed version | Evidence |
|---|---|---|---|
| Packagistgetkirby/cms | ECOSYSTEM: introduced 0; fixed 4.9.4 | 4.9.4 | OSV record ↗aggregator derived · 10 Sep 2026 |
| Packagistgetkirby/cms | ECOSYSTEM: introduced 5.0.0-alpha.1; fixed 5.4.4 | 5.4.4 | OSV record ↗aggregator derived · 10 Sep 2026 |
| composergetkirby/cms | <= 4.9.3 | 4.9.4 | GitHub advisory ↗upstream repository advisory · 18 Jun 2026 |
| composergetkirby/cms | >= 5.0.0-alpha.1, <= 5.4.3 | 5.4.4 | GitHub advisory ↗upstream repository advisory · 18 Jun 2026 |
High technical severity; prioritise exposed affected systems while verifying vendor guidance.
Fix not verified01
What, why and how
Kirby is an open-source content management system. Prior to 4.9.4 and 5.4.4, Kirby sites using the writer field in any blueprint allowed a scripting link to be included as the target of a link or email link in writer mark components, making the target clickable by the user who entered it and enabling self cross-site scripting in the Panel. This issue is fixed in versions 4.9.4 and 5.4.4.
What
Kirby is an open-source content management system. Prior to 4.9.4 and 5.4.4, Kirby sites using the writer field in any blueprint allowed a scripting link to be included as the target of a link or email link in writer mark components, making the target clickable by the user who entered it and enabling self cross-site scripting in the Panel. This issue is fixed in versions 4.9.4 and 5.4.4.
Why
The product does not neutralize or incorrectly neutralizes javascript: or other URIs from dangerous attributes within tags, such as onmouseover, onload, onerror, or style.
How
An attacker operating through a network path may attempt exploitation when the stated preconditions are met. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
What
Kirby is an open-source content management system. Prior to 4.9.4 and 5.4.4, Kirby sites using the writer field in any blueprint allowed a scripting link to be included as the target of a link or email link in writer mark components, making the target clickable by the user who entered it and enabling self cross-site scripting in the Panel. This issue is fixed in versions 4.9.4 and 5.4.4.
Why
The product does not neutralize or incorrectly neutralizes javascript: or other URIs from dangerous attributes within tags, such as onmouseover, onload, onerror, or style.
How
An attacker operating through a network path may attempt exploitation when the stated preconditions are met. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
- Likely attack path
- a network path → Improper Neutralization of Script in Attributes in a Web Page → cause the confidentiality, integrity or availability impact described by the vendor
- Attack surface
- Network
- Privileges required
- None: unauthenticated exploitation is possible
- User interaction
- Active interaction required
- Attack complexity
- High: exploitation depends on specific conditions
- Security boundary
- Not a CVSS 4.0 base metric
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-83 ↗
CWE-83: Improper Neutralization of Script in Attributes in a Web Page. The product does not neutralize or incorrectly neutralizes javascript: or other URIs from dangerous attributes within tags, such as onmouseover, onload, onerror, or style.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:NCommon Vulnerability Scoring System 4.0: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACHighAttack complexity: Successful exploitation depends on specific conditions outside the attacker's direct control.ATNoneAttack requirements: No additional deployment or execution condition is required.PRNonePrivileges required: The attacker does not need an account or existing privileges.UIActiveUser interaction: A user must take a deliberate action for exploitation to succeed.VCHighVulnerable-system confidentiality: A successful attack can cause a major loss.VIHighVulnerable-system integrity: A successful attack can cause a major loss.VANoneVulnerable-system availability: No direct loss is represented by this metric.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: No direct loss is represented by this metric.- Post-exploitation / living off the land
- No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Fix not verified
- Affected
- kirby: < 4.9.4, >= 5.0.0, < 5.4.4
- Fixed
- No fixed version is explicitly recorded in the structured CVE data.
- Action
- No verified patch reference is present in the current structured sources. Check the vendor advisory before making a change.
- Workaround
- No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04
Evidence and provenance
Published 9 Jul 2026 · Last source change 10 Jul 2026, 14:11 UTC · CWE-83 · Improper Neutralization of Script in Attributes in a Web Page
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2026-42671
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD not scheduled
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.